At the PTS blog, Excel charting whiz Jon Peltier takes an all-too-common type of crappy chart and walks the reader through his methods for analyzing and improving it. He starts with this:
… and ends up with this far better version:
The second version is far clearer and more scaleable — not to mention that it’s more correct mathematically. (He alters the bars to make them all the same width; this does away with any questions about whether the varying widths mean anything, and if so, what that might be.)
Overall, Peltier’s site is a handy resource, with pages of newbie-friendly tutorials and tips here. Thanks, Jon.